1. Technical Field
This invention relates to surface winding and unwinding of cloth, paper, metal, or plastic webs and the like from web rolls. The present invention utilizes an equalizing roll to be used in manufacturing for providing equal tension across a web, belt, or sheet of material during winding and conveying operations such as used in polymer film processing applications, corrugators, paper machines, printing presses, cloth winders and metal winding operations.
2. Background Information
The present invention comprises an equalizing roll which may be used as a stand alone unit or in a tracking apparatus for stabilizing the run of a material web which is being rolled off of or onto a drum or through a series of rollers. The present invention is designed to provide a method of optimally stabilizing, controlling the tension, controlling the slack, and the direction of a web, belt or sheet of material while the web is traveling between rolls.
One application is in the drying section of a high speed paper machine where the paper web to be dried meanders over drying cylinders. The present equalizing roll is also useable in connection with a xe2x80x9ctransfer foilxe2x80x9d, i.e. a device for transferring the paper web from the press section to the drying section such as described in U.S. Pat. No. 4,551,203 [Eskelinen]. The present invention may also be utilized for stabilizing and controlling the tension of a paper web of paper coaters. It is contemplated that the present invention can also be used in the fabric industry; plastics film, sheet, and tape industry; and in the metal film and foil industry. The invention may be used in small diameter, narrow width applications measurable in centimeters on inches or industrial operations wherein the rolls may extend thirty to fifty feet in length or longer depending on the application.
The equalizing roll of the present invention in the paper industry solves the problem of wrinkles and slack being formed in the paper or plastic film web during processing by an apparatus such as is described in U.S. Pat. No. 4,441,263 [Vedenpaa]. The present invention provides a means to control the pressure conditions in the area where the paper web runs together with a backing belt on a receiving drying cylinder and across the entire width of the paper web extending across the entire length of the drying cylinder or other such conveyor assembly. As is generally known, air flow transverse to the drying section causes the edges of the paper web to flutter and/or the formation of wrinkles in the paper web as shown in FIG. 1. This occasionally causes the paper web to break or a plastic web to be stretched and permanently distorted. A stable, smooth run of the paper web requires that the forces resulting from the longitudinal tension of the paper web be equal. The longitudinal tension on the paper web caused by the drying cylinder in combination with a backing belt creates a region in the paper web where the curvature is irregular as viewed across the width of the paper web. In the center, the paper web bows out more heavily than on the edges resulting in stretching and deformation of the web.
Another application for the present invention is in the cloth industry to avoid wrinkling cloth being unwound from rolls on surface winders and unwinders, batchers, cradle let-offs and the like. As set forth in U.S. Pat. No. 5,431,358 [Alexander], hereby incorporated by reference, in the area where the support rolls engage the cloth roll, the cloth roll is indented presenting a shorter cloth roll radius at that point than the radius in the unengaged areas of the roll resulting in the formation of a bulge or bagging down in advance of the support roll. Sometimes, the bulge or loose pucker resulting from such bagging down advances entirely about the wound roll causing wrinkling, marking and uneven tension.
U.S. Pat. No. 1,738,170 [Cohen], U.S. Pat. No. 3,433,429 [Schnitzspahn] and U.S. Pat. No. 4,026,487 [Ales] illustrate efforts to solve the problem through compressible support roll covering wherein an effort is made to match the compressibility of the support roll to the compressibility of the wound web roll. An inflatable support roll and other efforts to solve the problem include uniform or continuously spaced fluting on the support rolls. Such fluting may be skewed or spiraled in respect to the longitudinal axis. A roll having spaced segments is illustrated in U.S. Pat. No. 1,093,913 [Church], whereas U.S. Pat. No. 3,239,163 [Ciniglio] illustrates uniformly spaced compressible fluting having upper surface areas conforming to the curvature of the flexible roll. Attempts to match or otherwise utilize the relative compressibility of the support rolls in relation to the compressibility of the wound rolls have met with limited success. Fluted rolls having uniform circumferential spacing result in vibration or chattering and sometimes mark the wound rolls with the pattern of the fluted segments due to the limited areas of support.
The present invention provides an equalizing roll means to equalize the tension of the web as the web runs over the rolls distributing the lateral forces so that any imbalance of lateral tension will cause the roll to pivot at its center permitting the roll to move forward on the side of least tension until the web tension is equalized across the entire roll.
The equalizing roller of the present invention is a universal mount idler roll that works off of a center pivot point and is able to swivel a selected amount preferably in a range of from about 0xc2x0 to about 15xc2x0. The, equalizing roll is placed before or after, and in alignment with, a plurality of idler rollers having a web roll or belt of material in order to maintain a constant tension of the web or sheet of material unrolling from a web roll to prevent stretching or wrinkling of the material and facilitating off rolling of the material in a straight line so that the sheet or ribbon does not want to veer to one side. Moreover, the tracking apparatus may be used in conventional conveyor assemblies to provide directional stability to a belt, sheet, or web of material being conveyed over at least one equalizing roll.
In one embodiment of the present invention, a common axis shaft is rigidly clamped to support means preventing rotation. In some applications it may be desirable to support the shaft on two shaft support bearings providing for rotation; however, oscillation may occur if the roll is not perfectly balanced or if the pivoting-rotary bearing has experienced wear making control of the roll difficult. Mounted in the center of the shaft is a self-aligning pivoting-rotary bearing assembly having an inner convex ball and an outer concave socket portion disposed within a housing sleeve. The single center pivoting-rotary bearing assembly is mounted inside a hollow cylinder or roll machined to be in balance with respect to the centrally disposed pivoting-rotary bearing assembly. The mating of the concave and convex portions of the pivoting-rotary bearing permits a selected degree of lateral rotation and allows the roll to rotate independently of the shaft. As the web runs over the roll, any imbalance of lateral tension will cause the roll to pivot at its center permitting the roll to move forward on the side of least tension until the web tension is equalized across the entire roll.
More particularly, the present invention provides an equalizing roll for controlling web tension including a longitudinal shaft having distal ends rotatably supported by a pair of shaft support bearings, a self-aligning center pivoting-rotary bearing assembly having an inner ball portion fixedly connected to the weighted center of the shaft and an outer socket portion fixedly connected to the weighted center of the cylindrical roll coaxially mounted around the shaft, wherein the deflection of the roll with respect to the shaft is in the range of from about 1xc2x0 to about 10xc2x0, and most preferably about 6xc2x0. A compressible pivoting-rotary bearing of selected rigidity may be utilized between the roll and shaft at one or more selected positions to limit or control oscillations of the roll with respect to the shaft.
Another alternate embodiment of the present invention provides for a double equalizing roll for use in high speed operations, such as printing, to minimize vibration and provide additional rotational stability. The double equalizing roll utilizes a stationary shaft mounted horizontally on clamped rigid supports preventing rotation. Mounted in the center of the axis shaft is a pivoting bearing assembly having convex and concave portions disposed within a pivoting sleeve. The pivoting bearing assembly is centrally mounted inside the sleeve formed from a hollow cylinder or roll machined to be in balance with respect to the centrally disposed bearing assembly. At least one pin extends upward from the shaft into a mating slot formed in the pivoting sleeve preventing rotation thereof. The mating of the concave and convex portions of the pivoting bearing permits a selected degree of lateral rotation in a range of from about 1xc2x0 to about 10xc2x0. The stationary shaft and pivoting sleeve is placed coaxially within a rotating sleeve having a greater diameter than the pivoting sleeve. The rotating sleeve is mounted upon at least two rotary bearings on either side of pivoting bearing assembly. As the web runs over the pivoting sleeve, any imbalance of lateral tension will cause the pivoting sleeve to pivot at its center with respect to the longitudinal axis of the shaft permitting the pivoting sleeve to move upward on the side of least tension until the web tension is equalized across the pivoting sleeve while the exterior rotating sleeve rotates about the pivoting sleeve. The double equalizing roll provides a means for compensating to the tension and weight distribution of the web for high speed operations and minimize maintenance due to wear on the pivoting bearing assembly.
Accordingly, it is an important object of the present invention to provide a means for winding and unwinding paper, film, plastic, cloth or metal webs and avoid the problem of wrinkling, stretching, and marking of the web.
It is another object of the present invention to provide an equalizing roll to control the tension of a web to prevent the web from veering to one side.
It is another object of the present invention to provide an equalizing roll to control oscillation by use of a central pivoting means.
It is yet another object of the present invention to use a single pivoting-rotary bearing as a central pivoting means.
It is another object of the present invention to utilize the equalizer roll in tools such as with belt sanders or other equipment utilizing alignable belts.
Furthermore, one tracking assembly apparatus of the present invention comprises an equalizing roll, and an adjustable control arm assembly comprising at least one pair of pivoting arm assemblies. Each pivoting arm assembly includes a sensor arm linked to a steering arm by a means for pivoting. The sensor arm is in cooperative engagement with a web of material. The steering arm is in cooperative engagement with the equalizing roll. Whereby misalignment of the web of material moves the sensor arm pivotally linked to the steering arm exerting pressure on the equalizing roll correcting the alignment of the web material.
It is another object of the invention to utilize the equalizing roll in combination with an adjustable control arm assembly in cooperative engagement with an equalizer roll and the web of material to sense misalignment of the belt or web of material conveyed thereon and correct the alignment or tracking of the material by proportional adjustment of the equalizing roll.
A second tracking and repositioning assembly apparatus of the present invention comprises at least one pivoting conveyor roll which is pivotable and rotatably supported at its center in order to provide axial movement about a bearing assembly which is located at the weighted center point of the roll. The roll is positioned over a longitudinally fixed shaft extending through the conveyor roll and having the distal ends of the shaft fixedly housed within support members located at each end of the shaft; the bearing assembly has an aperture or bore for positioning around and accommodating the fixed shaft therethrough and connects to a cylindrical sleeve coaxially mounted about and spaced apart from the fixed shaft with the bearing assembly being positioned and balanced at a weighted center of the conveyor roll. The cylindrical sleeve extends outward to points proximate support members and through respective apertures in a pair of guide blocks, which are means for repositioning a web of material conveyed over the conveyor roll, and which guide blocks are disposed at each end of the cylindrical sleeve of the conveyor roll. The guide blocks are capable of accommodating both forward and rearward motion of the cylindrical sleeve and roll in the direction and counterdirection of movement of the web of material which passes over the cylindrical sleeve and conveyor roll by a horizontal translational motion in the direction of the movement. The cylindrical sleeve is also deflectable in forward and rearward directions swiveling in an arcuate motion in a horizontal plane about the bearing assembly housed within in accordance with the translational motion of the guide blocks as they move in the direction of movement of the web of material from a neutral position. The guide blocks move in response to frictional contact with the web of material with one of the guide blocks tracking and indicating a sideways misalignment of the web of material by having exerted against it a force which moves the guide block forward in the direction of movement, and moves the other guide block rearward in the counter-direction of movement, of the web of material causing the conveyor roll to pivot about the centrally located bearing assembly. The end of the conveyor roll which is pivoted forward steers the misaligned web of material away from that end of the conveyor roll and toward the center repositioning the web of material on the conveyor roll at or about its center; thus correcting the misalignment of the web of material. The conveyor roll structure utilized may be either the equalizing roll or the double equalizing roll described below in greater detail.
A third tracking and repositioning assembly apparatus of the present invention comprises at least one pivoting conveyor roll which is pivotable and rotatably supported at its center in order to provide axial movement about a bearing assembly which is located at the weighted center point of the roll. The roll is positioned over a longitudinally fixed shaft extending through the conveyor roll with end cap members at either end which cooperatively engage, through an interconnection pin and elongated slot, opposing cam members eccentrically mounted about the shaft having outwardly inclined inner surfaces for contacting the edge of the web. The cam members will frictionally contact the web edge, respond to the directional motion of the web by initiating rotational motion about the fixed shaft which, in turn, causes the pin to move outward in the elongated slot of the roller end cap causes a translational motion of the roller about the central bearing assembly to redirect an errant web to the central location of the roller system.
Other objects related to the practice of the inventions described herein will appear hereinafter.